<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>使用flex</title>
    <style>
        .container{
            display: flex;
            min-height: 400px;
        }
        .left{
            background-color: red;
            width: 300px;
        }
        .right{
            background-color: blue;
            width: 300px;
        }
        .center{
            background-color: yellow;
            flex: 1;
        }
    </style>
</head>
<body>
    <div class="container">
        <div class="left"></div>
        <div class="center"></div>
        <div class="right"></div>
    </div>
</body>
</html>